Every so often, my device will either partially or completely get wiped out, requiring me to re-install from a backup. One minute, everything seems fine; the next, apps stop working and upon a soft reset, everything is gone and back to either the original install or some partial install with some apps working and others not. This has happened to me at least a dozen times ... and twice in the past two days. I am not sure how to even start to diagnose this. I am suspecting that perhaps some of the memory on the device (either built-in or on my 8MB storage card) might be getting corrupted? Any thoughts as to how to diagnose this?

I'd try a hard reset, don't install any extra software, run it for a few days and see if this continues to happen. If so, it sounds like maybe your ROM (or storage card if you're installing there) is bad.

Well, I think I've narrowed the problem down to my storage card; this morning, the device crapped out again, and now the only file visible on the entire card is a device backup (using SPB backup) I made two days ago. Everything else on the card is gone, or at least not visible. Even when I place the card in my laptop, all I can see is that one backup file. Sigh ...

Are there any diagnostic tools that would tell me for sure that my microSD card is damaged? It is possible that something else on the 800w wiped out the card - I doubt it, but would like to eliminate that option.

That is a strange problem, can you transfer large files to the card when plugged into your PC? can you remove the card and insert it in the PC again and read the files? you should not need to format a new card unless something has caused a problem but as a last resort maybe reformat the card, other wise try another card in the phone, see if problem repeats.

Another update: I've downloaded an application for doing file recovery ... it is scanning the card now, but already has identified most of the (many) files that were on the card. It appears that perhaps it was the directory structure itself that got wiped out?